Power transmission and electric braking



Aug. 28, 1923.

. I 1,466,584 P. W. FORSBERG POWER TRANSMISSIONAND ELECTRIC BRAKING Filed Nov,. 11, 1922 2 Sheets-Sheet 1 "F gi.

MAIN CONTROLLER PI MALLEL .91

Inventor b3 W W Au 28, 1923. I 1,466,584

W. FORSBERG POWER TRANSMISSION AND ELECTRIC BRAKING- Filed Nov. 11, 1922 2 Sheets-Sh eet 2' I lnvehtor v Peter wforsberzg,

HisAULor -ne g.

' Schenectady, in the county of Schenectady,"

Patented Aug. 28, 1923.

UNITED STATES PATENT "OFFICE.

PETER W. FORSBERG, OF SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

POWER TRANSMISSION Ann nrincrnio BRAKING.

Application filed November 11, 1922. Serial No. 600,426.

To all whom it may concern:

Be it known that I, PETER W'. Fonsnnnc, a citizen of the United States, residing at State of New York, have invented certain new and useful Improvements in Power Transmission and Electric Braking, of which the following is a specification.

My invention relates to systems of control for dynamo electric machines and, in particular, it relates to systems wherein the dynamo electric machines either operate as motors to drive a load or are driven by the load and operate as generators to retard the load. 1

Although not limited to such use, the invention has a particular usefulness in the control of the electric driving'motors of an electric vehicle, such, for instance, as an electric locomotive or the like. v

In certain of its aspects, my invention is directed to a further development of the invention in power transmission and electric braking for which I obtained a Patent No. 1,421,931, dated July 4:, 1922. In the said patent there are shown,.described and broadtem for electric braking in which at least ly claimed several improved arrangements employing a plurality of dynamo electric machines. a portion of which is used as an cxciter for exciting the field windings of the remainder of the machines for electric brakmg". described in connection with archines as excitcrs for the remainder of the machines, Provision is then desirable for coordinating the action of the exciters and the braking machines so as to properly control the braking efi'ect.

One of the objects of my invention is to provide a simple and. effective control systwo of the dynamo electric machines serve as exciters for the remainder of the machines.

Another object of the invention is to provide a simple and effective arrangement whereby the exciters are connected in multiof the invention,

Theinvention of my said patent is shown and rangeinents in which a single dynamo elec tric machine serves as the exciter for the m p le with each other and the operation of the exciters is coordinated so that they cooperate effectively in the control of the braking cur rent.

Y Another objectof the invention is to provide simple and effective means whereby compensation is provided for variations in the generated potential of the braking ma chines and. ofthe exciters.

Another object of the invention is that the compensation for variations in the generated potential of the machines shall be the inherent effect of the connections between the machines.

These and further objects of the invention as'will be fully set forth hereinafter, and as will be apparent to those skilled in the art from an understanding of the invention, are attained by the systems shown in very sim plified diagramin the accompanying dra'w ings. i v

For an understanding ofthe principles companying drawings wherein l have illustrated my invention in very simplified diagrams in order that a quick and easy understanding of-the invention may be'had.

Referring to the drawings, Figure 1 shows a system of control for a plurality of dynae erate as series motors to drive a load or as generators toretard the load by electric braking; Fig, 2 is a simplified diagram of the'connections established for series motoring; Fig. 3 is a very simplified diagram of the connections established for parallel motoring; Fig; {l is a veryfsimp'lified dia gram of the connections established for seriesl braking inwhich two of the dynamo electric machines are connected so as to operate as self-excited exciters tor the remainder of the machines; and Fig. 5 is a very simplified diagram of the connections established for parallel braking in which two of the dynamo electric machines are connected in multiple relation with each other so that each of the machines operates as an exciter for a separate portion'of the remainder of the machines, the said. separate portions of the remainder of the machines being connected ina parallel relation with each other.

Referring to Fig. l, the dynamo electric machines are shown as of the series type having armaturesA to A inclusive and respective series fields F to F inclusive. These machines are arranged to be controlled by means of a main controller which is indicated as such on the drawing and a selective switch which is also indicated as such on the drawing. The main controller has an off position and a plurality of operative positions, a portion of the positions being for series relation of the controlled machines and a portion of the positions being for parallel relation of the controlled machines as indicated on the controller. The selective switch is provided with an oil and three operative positions. In the first operative position connections are established for motoring operation of the dynamo electric machines, in the second position connections are established as indicated in Fig. 4 for series braking, and in the final operative position connections are established for parallel braking. It will be understood that it metoring operation is desired. the selective switch will be thrown to its motoring position and then the main controller operated through its successive operative positions. In the initial operative positions o'lthe main controller, the machines will'be connected in series relation as shown in Fig. 2, and in the final operative positions of the main controller, the machines will be connected in parallel relation as shown in Fig. 3. The rcsistorsli to R inclusive are provided for controlling the speed of the machines duringz motoring and also for controlling the braking" effect during braking operations. It is believed that those skilled in the art will readily understand the connections established by the operation of the selective and the main controller without a detailed description thereof, and it is to be here noted that while the arrangement is shown as one in which the main controller and selective switch establish directly the machine circuits. 1 contemplate. that the invention will be embodied in remote control arrangements. It is believed that a clear understanding of the invention will be had from a description of Figs. 4; and 5 which disclose the essence of my invention.

t will be understood. that in any practical system of control arious interlocking connections will be required between the selective switch and the main controller in order that the proper coordination of these two devices may be had. However. the present invention is not limited to any particular set of interlockimc connections and those skilled in the art will readily provide suitable interlocking; connections from an understanding" of my prior Patent No. 1,421,931 above referred to.

Reference is now particularly had to Fig. l in which similar reference numerals designate similar parts of the apparatus shown in Figs. 1 2 and 3. In order to establish the connections as shown in Fig. 4 the se lective switch Fig. l, is first thrown to the series braking position and the main controller is moved toward theright through its successive series positions. As before stated, suitable interlocking connections will be necessary in order to prevent moving the main controller through the series position to the parallel position when brakoperations are desired. In the arrangement of Fig. l, the dynamo electric machines having armatures A and A and held windings i and F lQSl 'lQCtlVCly are connected so as to operate as exciters for the remainder of the dynamo electric machinesthe machines have armatures A to It." inclusive and field windings F to F in elusive. The exciter A is connected in a local. circuit with the field windings F and F and the field winding F of the other exciter. The eXciter A is connected in a local circuit with the field winding: and the field winding F of the e); These exciters are individually each con-- nected in a imamier set forth 'lully and broadly claimed in my said prior patent. The balancing or compensating resistor R is included in the braking circuit which comprises the armatures A? to A inclusive. This resistor is provided for varying the excitation of the exciters responsbaely to the value of the braking current. The resistors R, R R, R and 11 are under the control of the main controller l) so to vary at will the excitation o l the 01-;- citer fields F and F so as to tlicrelrv control the braking effort of the 7 achiner-s in the manner fully described a i broaill y claimed in my prior patent. it will be observed in this connection that 1 have arranged the circuits in such a manner that a single variable resis ace compr sir the resistors R It, It", and R regula es the brakingellect at the will of the operator for both of the er zciters simiiltaneously. hereby obtaining: a simplification and reliability ot operation, as will be fully apparent to those skilled in the art. It will also be noted that the excitation of both ex'citers is varied automatically and simultaneously by the voltage drop across the resistor One ot the principal diilir-ulties in term Acting up armatures in parallel is to balance the two parallel circuits so that there is no interchange of current between the armatures. This dilliculty is overcome in the arrange ment shown in Fig. l. by connecting the fields in such a manner that when one citer armature attempts to generate a higher potential than the other exciter armature. the field of the other armature is strengthened and its own field winding weakened. thereby balancing the circuit. hile con-- ditions are normal, the direction of the current will be as shown by the arrows. If

lrll

armature 5 should have a higher voltage than armature 6, it would tend to force cur rent through two paths, one path through resistances R and R to armature 6, and the other path through cxciter fields l and. Because of the tact that the current through the exciter fields is responsive to the voltage drop across the respective resistors R and R, if current flows from armature 5 to armature 6 through the circuit R it, it will be noted that the I. R. drop of R increases, while that of 1% decreases, there-- by increasing the field F and decreasing the excitation of field F causing A to generate a higher potential and. A to g nerate a lower potential, thereby balancing the circuit. Furthermore, because of the fact that. field F is in a local circuit with A and F is in a local circuit with A, the voltage 0t one exciter controls the excitation of the other. If there is an exchange of current between the exciter fields, the field of one exciter is strengthened and the field oi the other exciter is weakened so that .a balance is brought about. i

In order to obtain a certain range of speeds for the machines which is practical for the conditions of grade, etc. encountered during braking operation, it isisonietiines neces sary to provide a parallel braking ar rangement as shown in Fig. 5. The connections shown in this figure are those which areestablished by the operation of the selective switch (F 1) and the main controller. The selective switch will be thrown to the arallel brakim position as indicated and- F and F is furnished by the machine having an armature A and field F which also operates as a self excited exeiter. It will be noticed thatthe armature A is connected in a local circuit to the resistor R which is included in the braking circuit in which the armatures A and A are included. A variable resistance, comprising the resistors R R R and R simultaneously controls the excitation ofthe two exciters, in a man; ner similar to that explained in connection with Fig. 4-. A simplification is efiected in thata single variable resistance, functions to regulate at the will of the operator the braking efi'ectof the system. It will be noticed that the field F is connected in' its " will introduce more or less of the resistors R R, R and R in the field circuits of the exciters, thereby controlling at will the braking effect. The resistor R is connected in the circuit in such a manner that the main controller will not short circuit this section of the resistance. This is for the purpose of insuring that the main controller cannot be operated to cut out all resistance 11 the exciter field circuits and thereby produce an excessive braking effect. The resistor R included in the one branch of the parallel braking circuit, will automatically control the excitation oi the field F so as to regulate the excitation of the exciter A in accordance with the current in this branch of the braking circuit. Likewise the resistor R automatic lly'regulates the value of the current through the field F in accordance with the current in the other branch of the braking circuit. In the arrangement as shown in Fig; 5, it is necessary to not only balance the loads on the exciters A 1?, and A, Fflbut also to balance the regenerative currentthrough the dillerent separate regenerative circuits which are connected in parallel. The connections between the exciter fields F and F are such that thisautoinatic regulation is inherent in the connections. If the armatures A and A generate a higher voltage than the arinatures A and A'*, there will be an exchange of current from the armature A through the armatures A and A, exciter field F and exciter field F The full linearrows shown on the draw ing indicate the normal direction of the current in the various paths of the circuit dur ing braking operation while the circuits are in balance. The exchange of current between the armatures A A and il -A when the armatures il -A are generating a higher voltage than the arinatures A -A is indicated in dotted lines on the figure. It will be observed that this exchange current has the effect of strengthening the field F and weakening the field F thus automatioally establishing very quickly a balance between the ti o circuits. Likewise in case the arniatures fi -A generate a higher voltage restored. It the exciter armature A generates a higher voltage than armature A it -will cause the armatures A and A to generate a higher voltage and likewise an increase of the voltage of exciter A will cause the armatures A and A to generate a higher voltage.

in accordance with the provisions of the patent statutes 1 have described the principle of operation oit my invention together with the apparatus which I now consider to rep resent the best embodiment thereof, but I desire to have it understood that the apparatus shown is only illustrative and that the invention may be carried out by other means.

lVhat I claim as new and desire to secure by Letters Patent oi? the lnited States, is

1. In a system of control for electric braking, a plurality of dynamo electric machines, at least two of said machines COIUNBTiiGQl to operate as exciters for the remainder or? '1 machines, each of said exciters connected :1. separate local circuit with a substantially equal part of the field windings o f said remainder of the machines. and a variable resistor forming a connection between the said local circuits for simultaneously varying the excitation of the said cxcitcrs.

2. In a system of control for electric braking, a plurality of dynamo elect 'ic machiner-z, at least two of said machines connected to operate as exciters for electric raking, each of the said exciters connected in a separate local circuit with the lield windings or a portion oil. the machines, a resistor common to the said local circuits for varying the braking current, and equalizin connections between the said exciters.

3. in a system of control for electric braking, a plurality of dynamo electric machines, at least two oi": said machines connected to operate as exciters for the remainder of the machines, each of said exciters connected in a separate local circuit 'ith a substantially equal part of the field windings of the said remainder of the machines, a resistance forming a connection between said local cir cuits for simultaneously varying" the excitation of the said exciters, and. equal zing; cennections between the fields oi the exciter for causing the current in the two oXciter armatures to be substantially equal.

a. In a system of control for electric brakinc, a plurality oi. dynamo electric machines, at least two of. said machines connected to operate as exciters for the ren'iainder of the machines, each of said exciters connected in separate local circuit with a substantially equal part of the field windings of the said remainder of the machines and the field winding of the other exciter, a resistor forming a connection between the said local circuits for simultaneously varying the e:-;citation oi the said exciters, and equalizing connections between the field windings of said exciters.

5. In a system of control for electric braking, a plurality of dynamo electric machines, at least two of said machines connected to operate as self-excited exciters tor the remainder of the machines, each 01 said exciters connected in a separate local cirto the exchange oi current between 'i; e said local circuits.

(3. In a system of control for electric oral;-

ing, a plurality of dynamo electric machines. at least two of said machines connected to operate as cxciters For the remainder oi: machines. each oi? said excitcrs supplying u excitation tor its separate individual part of the said remainder ot the machines, means for varying the excitation oi? the aid ere ciers inversely lo the braking current, and equalizing connections between the said e):- citers for aryingr the excitation of one oil the exciters in accordance with the gnauerated potential of another cxciter.

'T. In a system oil control for electric braking, a plurality of dynamo electric machines adapted to operate either as series motors for motoring operation or as generators for electric braking, at least two oi said machines connected to operate as exciters for the remainder of the machines, the armature of each of said exciters connected to a separate local circuit with a sub stantially equal p: rt ot the field windings of the said remainder of the machines and the field winding of another exciter, and means connecting the said local circuits in parallel. relation for varyin the braking effect ol the said machines.

8. In a system of control for electric braking, a resistor, a plurality oi dynamo electric machines, a portion oi the armatures 0t said machines connected in series with the resistor to torm a braking circuit, another portion of the armature com prisin gr at least two of the armatures connected in n'i'ultiple with each other in local shunt circuits to the resistor, each of the said lo al circuits including field winding oi the said machines.

9. In a system 0 control 1" or electric brakinc, a plurality 01" similar dynamo electric machines adapted to series motors or as generators, at least two of said machines connected to operate as exciters for the said. machines for braking: operation, and equalizinp; connections between the said ex'citcrs for compensating for variations in the genrated potential oi the machines.

10. In a system oi? control for electric braking, a plurality of dynamo electric machines, at least two of said machines connect ed to operate as self-excited exciters tor the remainder of the i achines. each of said exciters connected to supply the excitation for a separate individual part oi the said remainder of: the machines, means for varying the excitation of the said exciters inof dynamo electric machines adapted to either operate as series motors 'or asgenerators for electric braking, at least two of said machines operating as exciters for electric braking, each of the said exciters connected in, a local circuit with the field windi ings of a portlon of the sald machines, means forming part of the said local circuits for varying the excitation of the said machines responsively to the braking current, and connections between the field windings of the said exciters for compensating for variations of the generated potential of the machines. a

12. In a system of control for a plurality of dynamo electric machines having series fields and adapted to operate either as series motors for motoring operation or as generators for electric braking, at least two of said machines connected to excite the field windings of the remainder of the machines for electric braking, the said exciters connected in multiple with each other and each exciter armature connected in a local circuit with a portion of the field windings of said machines, and equalizing connections between the said exciters.

13. In a system of control for electric braking, plurality of dynamo electric machines adapted to operate either as series motors for motoring operation or as generators for electric braking, at least two of said machines connected to operate as exciters for the field windings of the remainder of the machines, a resistor, the armatures of the said remainder of the machines connected in series with the said resistor to form a braking circuit,each of the said exciters connected in a separate local circuit with the said resistor, and equalizing connections between the field windings of said exciters. for compensating for variations in the genera ed potential of the exciters.

14. In a system of control for electric chines, means for simultaneously .varying at will the excitation of said exciters, means for varying the excitation of said exciters inversely responsively to the value of the braking effect, and equalizing connections between the field windings of said exciters.

15. In a system of control for electric braking, a plurality of dynamo electric machines, at least two of said machines each connected in a local circuit to operate as an eXciter for a substantially equal part of the remainder of the machines and for the other exciter, the said remainder of the machines connected in series relation to form a braking circuit, a variable resistor in the said i braking circuit forming a multiple connection "for the said local circuits and for simultaneously varying the excitation of the said exciters, and equalizing connections between the eXciter field windings for equalizing the current in the exciter arinatures.

16. In a system of control for electric braking, a plurality of dynamo electric machines, at least two of said machines connected to operate as exciters for the field windings oi? the remainder of the machines, each of the said exciters connected in a separate local circuit with a portion of the field windings of the remainder of the machines, resistance connected to be traversed by braking current and connected with the field windings of said exciters for varying the excitation of the exciters inversely to the braking effect, a variable resistor common to the said local circuits for simultaneously varying at will the excitation of the said exciters, and equalizing connections between the field windings of said exciters.

17. In a system: of control for electric braking, a plurality of dynamo electric machines at least two of said machines connected in parallel relation with each other and each connected to operate as an exciter for a substantially equal part of the remain der of the machines, substantially equalparts of the armatures of the remainder of simultaneously varying at will the potential of the said exciters, and connections between the field windings of said exciters for compensating for variations in the generated potential of the exciters and the generated potential of the said parallel connected parts of the armatures of the said remainder of the machines. I V

18. In a system of control for electric braking, a plurality of dynamo electric machines, at least two of said machines connected to operate as self-excited exciters for the remainder of the machines, substantially equal parts of the-armatures of said remainder of the machines being connected in parallel relation, each of said exciters connected in a separate local circuit with a substantially equal part of the field windings oi the said remainder of the machines, a variable resistor forming a connection between the said local circuits for simultaneously val-yin the excitation of the said exciters, and nae-ans v substantially equalizing the current in the arinatiu'e oi the said ren'iainder oi' the iiaachines, comprising an equalizing connee tion between the armatures of the remainder ct the machines which causes inter change of current between the arn'iatures of the remainder of the machines to vary the potentials of the said exciters in ooposite directions.

19. In a system 0i." control for electric braking, a plurality of dynamo electric niachlnes, at least two of said machines consented to operate as self-excited exciters for remainder the machines, substantially equal parts of the armature of said reinainder oi the machines connected in parallel re lation, each of said exciters connected in a separate local circuit with a substantially equal part oi the field windings of the said remainder of the machines, a variable resistor forming; a connection between the said local ircuits for simultaneously varying the excitation of the said exciters, and means for substantially equalizing the current of the ariuatiu-es of the said ren'iainder of the machines comprising an equalizing connection between the armatures of the reinaindcr ot' the machines and the field windings of the said ez-iciters which causes an in terchange oi? current between the armatures oi the remainder of the machines to vary the excitation of one eXcitcr in one direction and the excitation of the other exciter in the op posite direction.

in witness whereof, I have hereunto my hand this 10th day of Noveuiher, 19:22.

PETER V]. FORSBERG. 

